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US9509462B2 - Radio communication system, user terminal, radio base station apparatus and radio communication method - Google Patents

Radio communication system, user terminal, radio base station apparatus and radio communication method Download PDF

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Publication number
US9509462B2
US9509462B2 US14/386,982 US201314386982A US9509462B2 US 9509462 B2 US9509462 B2 US 9509462B2 US 201314386982 A US201314386982 A US 201314386982A US 9509462 B2 US9509462 B2 US 9509462B2
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cell
user terminal
base station
mode
pmi
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US20150085770A1 (en
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Satoshi Nagata
Jing Wang
Xiang Yun
Lan Chen
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NTT Docomo Inc
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NTT Docomo Inc
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L5/00—Arrangements affording multiple use of the transmission path
    • H04L5/003—Arrangements for allocating sub-channels of the transmission path
    • H04L5/0032—Distributed allocation, i.e. involving a plurality of allocating devices, each making partial allocation
    • H04L5/0035—Resource allocation in a cooperative multipoint environment
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/022—Site diversity; Macro-diversity
    • H04B7/024—Co-operative use of antennas of several sites, e.g. in co-ordinated multipoint or co-operative multiple-input multiple-output [MIMO] systems
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/06—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station
    • H04B7/0613—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission
    • H04B7/0615—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal
    • H04B7/0619—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal using feedback from receiving side
    • H04B7/0636—Feedback format
    • H04B7/0645—Variable feedback
    • H04B7/065—Variable contents, e.g. long-term or short-short
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L5/00—Arrangements affording multiple use of the transmission path
    • H04L5/003—Arrangements for allocating sub-channels of the transmission path
    • H04L5/0053—Allocation of signalling, i.e. of overhead other than pilot signals
    • H04L5/0057—Physical resource allocation for CQI
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W24/00—Supervisory, monitoring or testing arrangements
    • H04W24/10—Scheduling measurement reports ; Arrangements for measurement reports
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W28/00—Network traffic management; Network resource management
    • H04W28/02—Traffic management, e.g. flow control or congestion control
    • H04W28/06—Optimizing the usage of the radio link, e.g. header compression, information sizing, discarding information
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W28/00—Network traffic management; Network resource management
    • H04W28/16—Central resource management; Negotiation of resources or communication parameters, e.g. negotiating bandwidth or QoS [Quality of Service]
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/06—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station
    • H04B7/0613—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission
    • H04B7/0615—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal
    • H04B7/0619—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal using feedback from receiving side
    • H04B7/0621—Feedback content
    • H04B7/0632—Channel quality parameters, e.g. channel quality indicator [CQI]
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/06—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station
    • H04B7/0613—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission
    • H04B7/0615—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal
    • H04B7/0619—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal using feedback from receiving side
    • H04B7/0636—Feedback format
    • H04B7/0639—Using selective indices, e.g. of a codebook, e.g. pre-distortion matrix index [PMI] or for beam selection
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/06—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station
    • H04B7/0613—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission
    • H04B7/0615—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal
    • H04B7/0619—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal using feedback from receiving side
    • H04B7/0658—Feedback reduction
    • H04B7/066—Combined feedback for a number of channels, e.g. over several subcarriers like in orthogonal frequency division multiplexing [OFDM]
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W88/00—Devices specially adapted for wireless communication networks, e.g. terminals, base stations or access point devices
    • H04W88/08—Access point devices
    • H04W88/085—Access point devices with remote components

Definitions

  • the present invention relates to a radio communication system, a user terminal, a radio base station apparatus and a radio communication method that are applicable to a cellular system and so on.
  • UMTS Universal Mobile Telecommunications System
  • W-CDMA Wideband Code Division Multiple Access
  • HSDPA High Speed Downlink Packet Access
  • HSUPA High Speed Uplink Packet Access
  • a transmission rate of maximum approximately 2 Mbps can be achieved on the downlink by using a fixed band of approximately 5 MHz.
  • a successor system of an LTE system is also under study for the purpose of achieving further broadbandization and higher speed (for example, “LTE-advanced” (LTE-A)).
  • CA carrier aggregation
  • CCs Component Carriers
  • an agreement to make a single fundamental frequency block a frequency band for example, 20 MHz
  • the system band becomes 100 MHz.
  • inter-cell orthogonalization As a promising technique for further improving the system performance of the LTE system, there is inter-cell orthogonalization.
  • intra-cell orthogonalization is made possible by orthogonal multiple access on both the uplink and the downlink. That is to say, on the downlink, orthogonality is provided between user terminal UEs (User Equipment) in the frequency domain.
  • UEs User Equipment
  • W-CDMA Wideband Code Division Multiple Access
  • interference randomization by one-cell frequency re-use is fundamental.
  • CoMP coordinated multiple-point transmission/reception
  • a plurality of cells coordinate and perform signal processing for transmission and reception for one user terminal UE or for a plurality of user terminal UEs.
  • simultaneous transmission by a plurality of cells adopting precoding, coordinated scheduling/beam forming and so on are under study.
  • CQIs channel quality indicators
  • the radio base station apparatus re-calculates and updates the CQIs that are fed back, to adapt to these transmission modes. Upon such updating, it is necessary to prevent the increase of the overhead of feedback information, and still improve the accuracy of the updated CQIs.
  • the present invention has been made in view of the above, and it is therefore an object of the present invention to provide a radio communication system, a user terminal, a radio base station apparatus and a radio communication method, which, upon updating CQIs that are fed back when CoMP transmission is applied, can prevent the increase of the overhead of feedback information and still improve the accuracy of the updated CQIs.
  • the radio communication system of the present invention is a radio communication system comprising a plurality of radio base station apparatuses and a user terminal that is configured to be able to perform coordinated multiple point transmission/reception with the plurality of radio base station apparatuses, and, in this radio communication system, the user terminal has a generating section configured to generate feedback information such that channel state information of multiple cells is allotted to a plurality of subframes and transmitted, and a transmission section configured to feed back the generated feedback information to the radio base station apparatus of one of multiple coordinated points, using a physical uplink shared data channel, and the radio base station apparatus has an updating section configured to update the channel state information using the channel state information that is allotted in the plurality of subframes and fed back from the user terminal.
  • the user terminal of the present invention is a user terminal that is configured to be able to perform coordinated multiple point transmission/reception with a plurality of radio base station apparatuses, and this user terminal has a generating section configured to generate feedback information such that channel state information of multiple cells is allotted to a plurality of subframes and transmitted, and a transmission section configured to feed back the generated feedback information to the radio base station apparatus of one of multiple coordinated points, using a physical uplink shared data channel.
  • the radio base station apparatus of the present invention is a radio base station apparatus that coordinates with another radio base station apparatus and performs coordinated multiple point transmission/reception with a user terminal, and this radio base station apparatus has a determining section configured to determine a reporting mode that matches channel state information which the user terminal feeds back using a physical uplink control channel, a transmission section configured to report the determined reporting mode to the user terminal, a receiving section configured to receive channel state information of multiple cells, which the user terminal allots and transmits in multiple subframes, in accordance with the reported reporting mode, via a physical uplink shared data channel, and an updating section configured to update the channel state information using the channel state information of multiple cells that is allocated and received in multiple subframes.
  • the radio communication method of the present invention is a radio communication method for a plurality of radio base station apparatuses and a user terminal that is configured to be able to perform coordinated multiple point transmission/reception with the plurality of radio base station apparatuses, and this radio communication method includes the steps of, at the user terminal, generating feedback information such that channel state information of multiple cells is allotted to a plurality of subframes and transmitted, at the user terminal, feeding back the generated feedback information to the radio base station apparatus of one of multiple coordinated points, using a physical uplink shared data channel, and, at the radio base station apparatus, updating the channel state information using the channel state information that is allotted in the plurality of subframes and fed back from the user terminal.
  • FIG. 1 provides diagrams to explain coordinated multiple point transmission
  • FIG. 2 provides schematic diagrams to show configurations of radio base station apparatuses that are adopted in coordinated multiple point transmission/reception
  • FIG. 3 is a diagram to show a channel configuration of uplink radio resources
  • FIG. 4 is a diagram to show the relationship between CQI/PMI feedback types and PUSCH reporting modes
  • FIG. 5 is a diagram to explain a periodic CQI reporting method
  • FIG. 6 provides diagrams to show CSI feedback information transmission format configurations in conventional modes 3-0 and 3-1;
  • FIG. 7 is a diagram to show a CSI feedback information transmission format configuration in an extended PUSCH reporting mode (mode 3-0);
  • FIG. 8 is a diagram to show a CSI feedback information transmission format configuration in an extended PUSCH reporting mode (mode 3-1);
  • FIG. 9 is a diagram to show a CSI feedback information transmission format configuration in an extended PUSCH reporting mode (mode 3-1, transmission mode 9);
  • FIG. 10 provides diagrams to show CSI feedback information transmission format configurations in extended PUSCH reporting modes (mode 1-2), (mode 1-2, transmission mode 9);
  • FIG. 11 is a diagram to show a CSI feedback information transmission format configuration in an extended PUSCH reporting mode (mode 2-0);
  • FIG. 12 provides diagrams to show CSI feedback information transmission format configurations in extended PUSCH reporting modes (mode 2-2), (mode 2-2, transmission mode 9);
  • FIG. 13 provides diagrams to explain a CSI feedback mode type when CoMP is applied
  • FIG. 14 is a diagram to explain a system configuration of a radio communication system
  • FIG. 15 is a diagram to explain an overall configuration of a radio base station apparatus
  • FIG. 16 is a functional block diagram corresponding to a baseband processing section of a radio base station apparatus
  • FIG. 17 is a diagram to explain an overall configuration of a user terminal.
  • FIG. 18 is a functional block diagram corresponding to a baseband processing section of a user terminal.
  • Downlink CoMP transmission includes coordinated scheduling/coordinated beamforming (CS/CB), and joint processing.
  • Coordinated scheduling/coordinated beamforming refers to the method of transmitting a shared data channel to one user terminal UE from only one cell, and, as shown in FIG. 1A , allocates radio resources in the frequency/space domain, taking into account interference from other cells and interference against other cells.
  • joint processing refers to the method of transmitting a shared data channel from a plurality of cells, at the same time, by applying precoding, and includes joint transmission to transmit a shared data channel from a plurality of cells to one user terminal UE as shown in FIG. 1B , and dynamic point selection (DPS) to select one cell instantaneously and transmit a shared data channel as shown in FIG. 1C .
  • DPS dynamic point selection
  • the configuration to implement CoMP transmission/reception there are, for example, a configuration (centralized control based on an RRE configuration) to include a plurality of remote radio equipment (RREs) that are connected with a radio base station apparatus (radio base station apparatus eNB) by optical fiber and so on as shown in FIG. 2A , and a configuration (autonomous distributed control based on an independent base station configuration) of a radio base station apparatus (radio base station apparatus eNB) as shown in FIG. 2B .
  • FIG. 2A shows a configuration to include a plurality of remote radio equipment RREs, it is equally possible to use a configuration to include only single remote radio equipment RRE, as shown in FIG. 1 .
  • remote radio equipment RRE 1 and RRE 2 are controlled in a centralized fashion in a radio base station apparatus eNB.
  • the radio base station apparatus eNB central base station
  • each cell that is, each remote radio equipment RRE
  • the problems of signaling delay and overhead between radio base station apparatus eNBs, which become problems in an independent base station configuration, are insignificant, and high-speed radio resource control between cells becomes comparatively easy. Consequently, in the RRE configuration, it is possible to apply a method to use fast signal processing between cells such as simultaneous transmission of a plurality of cells, to the downlink.
  • a plurality of radio base station apparatus eNBs each perform radio resource allocation control such as scheduling.
  • timing information and radio resource allocation information such as scheduling are transmitted to one radio base station apparatus eNB, if necessary, using the X2 interface between the radio base station apparatus eNB of cell 1 and the radio base station apparatus eNB of cell 2 , for coordination between the cells.
  • CoMP transmission is applied to improve the throughput of user terminals located on cell edges. Consequently, control is executed to apply CoMP transmission when there is a user terminal located on a cell edge.
  • a radio base station apparatus determines the difference between the quality information of each cell (for example, RSRP (Reference Signal Received Power), RSRQ (Reference Signal Received Quality), or SINR (Signal-to-Interference plus Noise Ratio) from the user terminal, and, when the difference is equal to or less than a threshold value—that is, when there is little difference in quality between cells—decides that the user terminal is located on a cell edge, and applies CoMP transmission.
  • RSRP Reference Signal Received Power
  • RSRQ Reference Signal Received Quality
  • SINR Signal-to-Interference plus Noise Ratio
  • the radio base station apparatus decides that the user terminal is close to the radio base station apparatus of one cell and that the user terminal is near the center of a cell, and does not apply CoMP transmission.
  • the user terminal feeds back channel state information (CSI) for each of a plurality of CoMP cells to the radio base station apparatus (the radio base station apparatus of the serving cell). Also, the radio base station apparatus calculates CQIs for CoMP using each cell's CSI (in particular, CQI: Channel Quality Indicator) that is fed back, and updates the CSI for CoMP (for example, CQI).
  • CQI Channel Quality Indicator
  • signals to be transmitted on the uplink are mapped to adequate radio resources and transmitted from a mobile terminal apparatus to a radio base station apparatus.
  • user data (UE #1 and UE #2) is allocated to an uplink shared channel (PUSCH: Physical Uplink Shared Channel).
  • PUSCH Physical Uplink Shared Channel
  • control information is time-multiplexed with the PUSCH, and, when control information alone is transmitted, the control information is allocated to an uplink control channel (PUCCH: Physical Uplink Control Channel).
  • This control information to be transmitted on the uplink includes downlink quality information (for example, CQI), retransmission acknowledgement signals (ACK/NACK) in response to downlink shared channel (PDSCH: Physical Downlink Shared Channel) signals, and so on.
  • CQI downlink quality information
  • ACK/NACK retransmission acknowledgement signals
  • PDSCH Physical Downlink Shared Channel
  • CSI feedback methods in the LTE system (Rel-10), there are a method of sending feedback periodically using an uplink control channel (PUCCH) (periodic CSI reporting using the PUCCH), and a method of sending feedback aperiodically using an uplink shared channel (PUSCH) (aperiodic CSI reporting using the PUSCH).
  • PUCCH uplink control channel
  • PUSCH uplink shared channel
  • CA carrier aggregation
  • CCs component carriers
  • the capacity of PUSCH resources in one subframe is large, so that feedback information (CSI) in response to signals transmitted from multiple cells on the downlink is fed back in one transmission (one subframe) using the PUSCH.
  • CSI feedback information
  • the CSI of each of a plurality of CoMP cells is fed back to the radio base station apparatus of a predetermined cell (serving cell) using the PUSCH, the CSI of the cells is reported in one transmission (one subframe) using the PUSCH.
  • the present inventors have made an earnest study taking into account the above-described points, and found out that, when a user terminal feeds back CSI in a plurality of CoMP cells using the PUSCH, it is possible to reduce the overhead of feedback information by controlling the number of times of transmission and by controlling the combinations of signals. Furthermore, the present inventors have found out that it is possible to adequately feed back CSI in a plurality of CoMP cells by extending conventional formats.
  • FIG. 4 is a diagram to show the relationship between CQI/PMI feedback types and PUSCH reporting modes.
  • the CQI feedback types can indicate the case where the CQI to feed back corresponds to a wideband (system band), the case where the CQI to feed back corresponds to a subband selected by a user terminal, and the case where the CQI to feed back corresponds to a subband designated by a radio base station apparatus by a higher layer signal.
  • the PMI feedback types can indicate the case where there is no PMI to feed back, the case where there is one PMI to feed back, and the case where there are multiple PMIs to feed back.
  • Rel-10 provides for a mode (mode 1-2) combining a CQI feedback type to feed back the CQI of the wideband (hereinafter referred to as “WB CQI”) and a PMI feedback type to feed back a plurality of PMIs, a mode (mode 2-0) combining a CQI feedback type to feed back the CQI of a subband selected by a user terminal (hereinafter referred to as “SB CQI”) and a PMI feedback type not to feed back a PMI, a mode (mode 2-2) combining a CQI feedback type to feed back an SB CQI designated by a higher layer signal and a PMI feedback type to feed back a plurality of PMIs, a mode (mode 3-0) combining a CQI feedback type to feed back an SB CQI designated by a higher layer signal and a PMI feedback type not to feed back a PMI, and a mode (mode 3-1) combining a CQI feedback type to feed back an SB
  • the system band is formed with N subbands, and one subband is formed with k RBs (Resource Blocks).
  • a user terminal finds the CQI value of each of the N subbands (SB CQIs: CQI 1, CQI 2 . . . CQI N) and also finds the CQI value of the wideband (WB CQI).
  • a CQI report is triggered aperiodically, and, in one subframe, the CQI values of the N subbands (CQI 1, CQI 2 . . . CQI N), the CQI value of the wideband (WB CQI), and RI are fed back using the PUSCH.
  • CQIs for multiple cells are fed back for CoMP, (4-6+2N) bits ⁇ bit information of multiple cells are transmitted in one time (one subframe) using the PUSCH.
  • FIGS. 6A and 6B show a format configuration for transmitting CSI feedback information for one cell ( FIG. 6A ) in a conventional PUSCH reporting mode (mode 3-0), and a format configuration for transmitting CSI feedback information upon three-cell CoMP (cells A, B and C) ( FIG. 6B ).
  • SB CQIs of eight subbands and a WB CQI of one system band are arranged in PUSCH resources in one subframe.
  • SB CQIs of eight subbands and a WB CQI of one system band are arranged in PUSCH resources in one subframe.
  • the CSI feedback information to be arranged in the PUSCH resources in one subframe increases, and the overhead of uplink feedback information increases.
  • CSI information of multiple cells (WB CQIs and SB CQIs), which is transmitted in one subframe in the conventional PUSCH reporting mode, is allotted to PUSCHs in a plurality of subframes and transmitted.
  • WB CQIs and SB CQIs When CoMP by three cells A, B and C is applied, in the PUSCH resources to be transmitted in the first subframe, the WB CQI of cell A, the CQIs of three subbands of cell A (CQI A ⁇ 3), the CQIs of three subbands of cell B (CQI B ⁇ 3), and the CQIs of two subbands of cell C (CQI C ⁇ 2) are arranged.
  • the WB CQI of cell B In the PUSCH resources to be transmitted in a second subframe, which is the next subframe following the first subframe, the WB CQI of cell B, the CQIs of three subbands among the rest of the subbands of cell B (CQI B ⁇ 3), the CQIs of three subbands among the rest of the subbands of cell C (CQI C ⁇ 3), and the CQIs of two subbands among the rest of the subbands of cell A (CQI A ⁇ 2) are arranged.
  • the WB CQI of cell C the CQIs of the remaining three subbands of cell C (CQI C ⁇ 3), the CQIs of the remaining three subbands of cell A (CQI A ⁇ 3), and the CQIs of the remaining two subbands of cell B (CQI B ⁇ 2) are arranged.
  • the radio base station apparatus reports the new PUSCH reporting mode (extended mode 3-0) to a user terminal by means of a higher layer signal.
  • the new PUSCH reporting mode extended mode 3-0
  • either a periodic PUSCH or an aperiodic PUSCH is reported as the PUSCH to use for CSI feedback.
  • the radio base station apparatus is able to allocate a periodic PUSCH to uplink radio resources by, for example, triggering the PUSCH periodically.
  • the radio base station apparatus may transmit PUSCH triggering bits to the user terminal by means of a downlink control signal (PDCCH) or a higher layer signal with arbitrary timing, and the user terminal may receive the PUSCH triggering bits and allocate the PUSCH periodically only for a certain period of time.
  • PDCCH downlink control signal
  • the radio base station apparatus may also transmit triggering bits for triggering the aperiodic PUSCH to the user terminal through a downlink control signal (PDCCH).
  • a downlink control signal (PDCCH)
  • the user terminal Upon detecting the aperiodic PUSCH triggering bits from the downlink control signal (PDCCH), the user terminal allocates the PUSCH to uplink radio resources. Since CSI feedback information for multiple cells is allotted to PUSCHs in a plurality of subframes and transmitted, once the aperiodic PUSCH is triggered, PUSCH transmission is carried out for a plurality of subframes. In another extended PUSCH reporting mode to be described later, CSI feedback information is transmitted using a periodic PUSCH or an aperiodic PUSCH as well.
  • a user terminal where the new PUSCH reporting mode (extended mode 3-0) is applied allots and transmits CSI information of multiple cells (WB CQIs and SB CQIs) in a plurality of subframes, as shown in FIG. 7 .
  • the radio base station apparatus acquires the CSI of multiple cells from the PUSCHs received on the uplink.
  • the CSI information of multiple cells A, B and C is complete.
  • the new PUSCH reporting mode extended mode 3-0
  • the amount of information of CSI feedback information with the conventional PUSCH reporting mode (mode 3-0) shown in FIG. 6B is reduced to approximately 1 ⁇ 3 (by 66.7%).
  • a user terminal finds the CQI value of each of N subbands (CQI 1, CQI 2 . . . CQI N) and also finds the CQI value of the wideband (WB CQI). Furthermore, the user terminal finds the PMI of the wideband.
  • a CQI report is triggered aperiodically, and, in one subframe, the CQI values of N subbands (CQI 1, CQI 2 . . . CQI N), the CQI value of the wideband (WB CQI), and the PMI and RI of the wideband are fed back using the PUSCH.
  • a WB CQI (4 or 8 bits)+SB CQIs (2N or 4N bits)+a PMI (2 or 4 bits)+an RI (0-2 bits) are transmitted in one subframe using the PUSCH.
  • FIGS. 6C and 6D a format configuration for transmitting CSI feedback information of one cell ( FIG. 6C ) in the conventional PUSCH reporting mode (mode 3-1), and a format configuration for transmitting CSI feedback information upon three-cell CoMP (cells A, B and C) ( FIG. 6D ) are shown.
  • SB CQIs of eight subbands, one WB CQI, and one WB PMI are arranged in the PUSCH resources in one subframe.
  • SB CQIs of eight subbands, one WB CQI, and one WB PMI are arranged in the PUSCH resources in one subframe.
  • the CSI feedback information to be arranged in the PUSCH resources in one subframe increases, and the overhead of uplink feedback information increases.
  • CSI information of multiple cells WB CQIs, WB PMIs and SB CQIs
  • WB CQIs CSI information of multiple cells
  • the WB PMI of cell A (PMI A)
  • the WB CQI of cell A (CQI A)
  • the SB CQIs of three subbands of cell A (CQI A ⁇ 3)
  • the SB CQIs of three subbands of cell B (CQI B ⁇ 3)
  • the SB CQIs of two subbands of cell C (CQI C ⁇ 2)
  • the WB PMI of cell B (PMI B), the WB CQI of cell B (CQI B), the CQIs of three subbands among the rest of the SB CQIs of cell B (CQI B ⁇ 3), the CQIs of three subbands among the rest of the SB CQIs of cell C (CQI C ⁇ 3), and the CQIs of two subbands among the rest of the SB CQIs of cell A (CQI A ⁇ 2) are arranged.
  • the WB PMI of cell C (PMI C), the WB CQI of cell C (CQI B), the SB CQIs of the remaining three subbands of cell C (CQI C ⁇ 3), the SB CQIs of the remaining three subbands of cell A (CQI A ⁇ 3), and the SB CQIs of the remaining two subbands of cell B (CQI B ⁇ 2) are arranged.
  • the radio base station apparatus acquires the CSI of multiple cells from the PUSCHs received on the uplink.
  • the CSI information of multiple cells A, B and C is complete.
  • the new PUSCH reporting mode extended mode 3-1
  • the amount of information of CSI feedback information with the conventional PUSCH reporting mode is reduced to approximately 1 ⁇ 3 (by 66.7%).
  • the conventional PUSCH reporting mode (mode 3-1, transmission mode 9 using a double codebook)
  • two kinds of WB PMIs (W1 and W2) are included in CSI feedback information as shown in FIG. 6E . Consequently, in the conventional PUSCH reporting mode (mode 3-1, transmission mode 9 using a double codebook), for every one cell, the CQI values of N subbands (CQI 1, CQI 2 . . . CQI N), the CQI value of the wideband (WB CQI), two kinds of WB PMI (W1) and WB PMI (W2) are produced as CSI feedback information.
  • the overhead of the CSI feedback information increases.
  • a new PUSCH reporting mode (extended mode 3-1, transmission mode 9 using a double codebook), which is given by extending the conventional PUSCH reporting mode (mode 3-1, transmission mode 9 using a double codebook) to reduce the overhead, will be described with reference to FIG. 9 .
  • CSI information of multiple cells WB CQIs, WB PMIs (W1 and W2) and SB CQIs
  • WB CQIs WB CQIs
  • WB PMIs W1 and W2
  • SB CQIs CSI information of multiple cells
  • FIG. 9 when CoMP by three cells A, B and C is applied, in the PUSCH resources to be transmitted in the first subframe, the WB PMI of cell A (PMI A (W1)), the WB PMI of cell B (PMI B (W1)), the WB CQI of cell A (CQI A), and the SB CQIs of eight subbands of cell B (CQI B ⁇ 8) are arranged.
  • the WB PMI of cell C (PMI C (W1)), the WB PMI of cell B (PMI B (W2)), the WB CQI of cell B (CQI B), and the SB CQIs of eight subbands of cell C (CQI C ⁇ 8) are arranged.
  • the WB PMI of cell A (PMI A (W2)), the WB PMI of cell C (PMI C (W2)), the WB CQI of cell C (CQI C), and the SB CQIs of eight subbands of cell A (CQI A ⁇ 8) are arranged.
  • a user terminal where the new PUSCH reporting mode (extended mode 3-1, transmission mode 9 using a double codebook) is applied allots and transmits CSI information of multiple cells (WB PMI (W1), WB PMI (W2), WB CQIs and SB CQIs) to PUSCHs in a plurality of subframes as shown in FIG. 9 .
  • the radio base station apparatus acquires the CSI of multiple cells from the PUSCHs received on the uplink.
  • the CSI information of multiple cells A, B and C (WB PMI (W1), WB PMI (W2), WB CQIs and SB CQIs) is complete.
  • the new PUSCH reporting mode extended mode 3-1, transmission mode 9 using a double codebook
  • the amount of information of CSI feedback information per feedback is reduced to approximately 1 ⁇ 3 (by 66.7%).
  • a wideband CQI value (WB CQI), which gives the average of the CQI values of N subbands, and each subband's optimal PMI are reported.
  • WB CQI wideband CQI value
  • a CQI report is triggered aperiodically, and the CQI of the wideband, the SB PMI of each subband (PMI 1, PMI 2 . . . PMI N), subband position information of the SB PMIs, and RI are fed back to the radio base station apparatus in one subframe using the PUSCH.
  • the conventional PUSCH reporting mode for every one cell, for example, a WB CQI (4 or 8 bits)+SB PMIs (2N or 4N bits)+an RI (0-2 bits) are transmitted in one subframe using the PUSCH.
  • a WB CQI (4 or 8 bits)+SB PMIs (2N or 4N bits)+an RI (0-2 bits) are transmitted in one subframe using the PUSCH.
  • the CSI feedback information of the CQI report to be arranged in the PUSCH resources in one subframe increases, and the overhead of uplink feedback information increases.
  • CSI information of multiple cells (WB CQIs, SB PMI 1, SB PMI 2 . . . SB PMI N) is distributed over a plurality of subframes and transmitted.
  • WB CQIs, SB PMI 1, SB PMI 2 . . . SB PMI N CSI information of multiple cells
  • FIG. 10A when CoMP by three cells A, B and C is applied, in the PUSCH resources to be transmitted in the first subframe, the WB CQI of cell A, the SB PMIs of three subbands of cell A (PMI A ⁇ 3), the SB PMIs of three subbands of cell B (PMI B) ⁇ 3), and the SB PMIs of two subbands of cell C (PMI C ⁇ 2) are arranged.
  • the WB CQI of cell B the SB PMIs of three subbands among the rest of the subbands of cell B (PMI B ⁇ 3), the SB PMIs of three subbands among the rest of the subbands of cell C (PMI C ⁇ 3), and the SB PMIs of two subbands among the rest of the subbands of cell A (PMI A ⁇ 2) are arranged.
  • the WB CQI of cell C the SB PMIs of three subbands among the rest of the subbands of cell C (PMI C ⁇ 3), the SB PMIs of three subbands among the rest of the subbands of cell A (PMI A ⁇ 3), and the SB PMIs of two subbands among the rest of the subbands of cell B (PMI B ⁇ 2) are arranged.
  • a user terminal where the new PUSCH reporting mode (extended mode 1-2) is applied allots and transmits CSI information of multiple cells (WB CQIs and SB PMIs) to PUSCHs in a plurality of subframes as shown in FIG. 10A .
  • the radio base station apparatus acquires the CSI of multiple cells from the PUSCHs received on the uplink.
  • the CSI information of multiple cells A, B and C (WB CQIs and SB PMIs) is complete.
  • the new PUSCH reporting mode extended mode 1-2
  • the amount of information of CSI feedback information with the conventional PUSCH reporting mode can be reduced.
  • CSI feedback information includes two kinds of WB PMIs (W1 and W2) for every one cell. Consequently, in the conventional PUSCH reporting mode (mode 1-2, transmission mode 9 using a double codebook), for every one cell, the SB PMIs of N subbands (PMI 1, PMI 2 . . . PMI N), the CQI value of the wideband (WB CQI), and two kinds of WB PMI (W1) and WB PMI (W2) are produced as CSI feedback information.
  • the overhead of the CSI feedback information increases.
  • a new PUSCH reporting mode (extended mode 1-2, transmission mode 9 using a double codebook), which is given by extending the conventional PUSCH reporting mode (mode 1-2, transmission mode 9 using a double codebook) to reduce the overhead, will be described with reference to FIG. 10B .
  • CSI information of multiple cells (WB CQIs, WB PMIs (W1 and W2), and SB PMIs) is allotted to a plurality of subframes and transmitted.
  • WB CQIs, WB PMIs (W1 and W2), and SB PMIs are allotted to a plurality of subframes and transmitted.
  • FIG. 10B when CoMP by three cells A, B and C is applied, in the PUSCH resources to be transmitted in the first subframe, the WB PMI of cell A (PMI A (W1)), the WB PMI of cell B (PMI B (W1)), the WB CQI of cell A (CQI A), and the SB PMIs of eight subbands of cell B (PMI B ⁇ 8) are arranged.
  • the WB PMI of cell C (PMI C (W1)), the WB PMI of cell B (PMI B (W2)), the WB CQI of cell B (CQI B), and the SB PMIs of eight subbands of cell C (SB PMI C ⁇ 8) are arranged. Furthermore, in the PUSCH resources to be transmitted in a third subframe, the WB PMI of cell A (PMI A (W2)), the WB PMI of cell C (PMI C (W2)), the WB CQI of cell C (CQI C), and the SB PMIs of eight subbands of cell A (SB PMI A ⁇ 8) are arranged.
  • a user terminal where the new PUSCH reporting mode (extended mode 1-2, transmission mode 9 using a double codebook) is applied allots and transmits CSI information of multiple cells (WB PMI (W1), WB PMI (W2), WB CQIs and SB PMIs) to PUSCHs in a plurality of subframes as shown in FIG. 10B .
  • the radio base station apparatus acquires the CSI of multiple cells from the PUSCHs received on the uplink.
  • the CSI information of multiple cells A, B and C (WB PMI (W1), WB PMI (W2), WB CQIs and SB PMIs) is complete.
  • the new PUSCH reporting mode extended mode 1-2, transmission mode 9 using a double codebook
  • the amount of information of CSI feedback information with the conventional PUSCH reporting mode can be reduced.
  • a user terminal selects M subbands having greater CQI values from N subbands, and reports the average value (SB CQI) of the CQI values of the M selected subbands, position information of the M selected subbands, and WB CQI, which gives the average CQI of the entire band.
  • SB CQI average value
  • a new PUSCH reporting mode (extended mode 2-0), which is given by extending a conventional PUSCH reporting mode (mode 2-0) to reduce the overhead, will be described with reference to FIG. 11 .
  • CSI information of multiple cells (WB CQIs, SB position information, and SB CQIs to be the average CQI value of M selected subbands) is allotted to PUSCHs in a plurality of subframes and transmitted.
  • WB CQIs, SB position information, and SB CQIs to be the average CQI value of M selected subbands is allotted to PUSCHs in a plurality of subframes and transmitted.
  • the WB CQI of cell A, the average CQI value of M subbands selected in cell B (CQI), and position information of the M subbands selected in cell B (the parts of diagonal lines in FIG. 11 ) are arranged.
  • the WB CQI of cell B In the PUSCH resources to be transmitted in a second subframe, the WB CQI of cell B, the average CQI value of M subbands selected in cell C (CQI), and position information of the M subbands selected in cell C (the parts of diagonal lines in FIG. 11 ) are arranged. Furthermore, in the PUSCH resources to be transmitted in a third subframe, the WB CQI of cell C, the average CQI value of M subbands selected in cell A (CQI), and position information of the M subbands selected in cell A (the parts of diagonal lines in FIG. 11 ) are arranged.
  • a user terminal where the new PUSCH reporting mode (extended mode 2-0) is applied allots and transmits CSI information of multiple cells (WB CQIs, SB position information, and CQIs (M-subband averages)) to PUSCHs in a plurality of subframes as shown in FIG. 11 .
  • the radio base station apparatus acquires the CSI of multiple cells from the PUSCHs received on the uplink.
  • the CSI information of multiple cells A, B and C (WB CQIs, SB position information, and SB CQIs) is complete.
  • the new PUSCH reporting mode extended mode 2-0
  • the amount of information of CSI feedback information with the conventional PUSCH reporting mode can be reduced.
  • a new PUSCH reporting mode (extended mode 2-2), which is given by extending a conventional PUSCH reporting mode (mode 2-2) to reduce the overhead, will be described with reference to FIG. 12A .
  • a user terminal selects M subbands having the largest CQI values from N subbands, and reports the average value of the CQI values of the M selected subbands (CQI), an optimal PMI for the average CQI value of the M selected subbands (PMI), a WB CQI, and a WB PMI to the radio base station apparatus.
  • CQI CQI
  • PMI PMI
  • WB CQI WB CQI
  • WB PMI WB PMI
  • the user terminal For every one cell, the user terminal feeds back a WB CQI (4 or 8 bits)+SB CQIs (2 or 4 bits)+SB position information (L bits)+(an SB PMI+a WB PMI) (4 or 8 bits)+an RI (0-2 bits) to the radio base station apparatus using the PUSCH of one subframe. Consequently, there is a problem that, when the user terminal tries to feed back CSI information of multiple cells using the PUSCH in one subframe for CoMP, the overhead of the CSI feedback information increases.
  • a new PUSCH reporting mode (extended mode 2-2), which is given by extending a conventional PUSCH reporting mode (mode 2-2) to reduce the overhead, will be described with reference to FIG. 12A .
  • CSI information of multiple cells WB CQIs, WB PMIs, SB position information, average CQIs of M selected subbands, and optimal PMIs for the average CQIs of M selected subbands is allotted to PUSCHs in a plurality of subframes and transmitted. As shown in FIG.
  • the WB CQI of cell A (CQI A), the WB PMI of cell B (PMI B), an SB CQI to be the average CQI value of M subbands selected in cell A (CQI A), the average CQI value of the M subbands selected in cell A (CQI), an optimal PMI for the average CQI value of M subbands selected in cell B, and position information of the M subbands selected in cell B (the parts of diagonal lines in FIG. 12A ) are arranged.
  • the WB CQI of cell B (CQI B), the WB PMI of cell C (PMI C), the average CQI value of the M subbands selected in cell B (CQI), an optimal PMI for the average CQI value of M subbands selected in cell C (PMI), and position information of the M subbands selected in cell C (the parts of diagonal lines in FIG. 12A ) are arranged.
  • the WB CQI of cell C (CQI C)
  • the WB PMI of cell A (PMI A)
  • the average CQI value of the M subbands selected in cell C (CQI)
  • an optimal PMI for the average CQI value of the M subbands selected in cell A (PMI)
  • position information of the M subbands selected in cell A (the parts of diagonal lines in FIG. 12A )
  • a user terminal where the new PUSCH reporting mode (extended mode 2-2) is applied allots and transmits CSI information of multiple cells (WB CQIs, WB PMIs, SB position information, average CQI values (M subbands), and PMIs (which correspond to the average CQI values) in PUSCHs of a plurality of subframes, as shown in FIG. 12A .
  • the radio base station apparatus acquires the CSI of multiple cells from the PUSCHs received on the uplink.
  • the CSI information of multiple cells A, B and C (WB CQIs, WB PMI, SB position information, average CQI values (M subbands), and PMIs (which correspond to the average CQI values)) is complete.
  • the new PUSCH reporting mode extended mode 2-0
  • the amount of information of CSI feedback information with the conventional PUSCH reporting mode can be reduced.
  • a new PUSCH reporting mode (extended mode 2-2, transmission mode 9 using a double codebook), which is given by extending a conventional PUSCH reporting mode (mode 2-2, transmission mode 9 using a double codebook) to reduce the overhead, will be described with reference to FIG. 12B .
  • CSI feedback information includes two kinds of WB PMIs (W1 and W2) for every one cell. Consequently, in the conventional PUSCH reporting mode (mode 2-2, transmission mode 9 using a double codebook), two kinds of WB PMI (W1) and WB PMI (W2), a WB CQI, SB position information, an average CQI value (M subbands), and a PMI (which corresponds to the average CQI value) are produced as CSI feedback information for every one cell.
  • W1 and W2 transmission mode 9 using a double codebook
  • a new PUSCH reporting mode (extended mode 2-2, transmission mode 9 using a double codebook), which is given by extending a conventional PUSCH reporting mode (mode 2-2, transmission mode 9 using a double codebook) to reduce the overhead, will be described with reference to FIG. 12B .
  • CSI information of multiple cells WB CQIs, two kinds of WB PMI (W1) and WB PMI (W2), SB position information, average CQI values (M selected subbands), and PMIs (which correspond to the average CQI value) is allotted and transmitted in PUSCHs in a plurality of subframes. As shown in FIG.
  • the WB CQI of cell A when CoMP by three cells A, B and C is applied, in the PUSCH resources to be transmitted in the first subframe, the WB CQI of cell A, the WB PMI of cell A (W1), the WB PMI of cell B (PMI B), the average CQI value of M subbands selected in cell A (CQI), an optimal PMI for the average CQI value of M subbands selected in cell B, and position information of the M subbands selected in cell B (the parts of diagonal lines in FIG. 12B ) are arranged.
  • the WB CQI of cell B In the PUSCH resources to be transmitted in a second subframe, the WB CQI of cell B, the WB PMI of cell B (W2), the WB PMI of cell C (W1), the average CQI value of the M subbands selected in cell B (CQI), an optimal PMI for the average CQI value of the M subbands selected in cell C, and position information of the M subbands selected in cell C (the parts of diagonal lines in FIG. 12B ) are arranged.
  • the WB CQI of cell C the WB PMI of cell C (W2), the WB PMI of cell A (W2), the average CQI value of the M subbands selected in cell C (CQI), an optimal PMI for the average CQI value of the M subbands selected in cell A, and position information of the M subbands selected in cell A (the parts of diagonal lines in FIG. 12B ) are arranged.
  • a user terminal where the new PUSCH reporting mode (extended mode 2-2, transmission mode 9 using a double codebook) is applied allots and transmits CSI information of multiple cells (WB CQIs, WB PMI (W1), WB PMI (W2), SB position information, average CQI values of selected subbands, and optimal PMIs for the average CQI values) in PUSCHs in a plurality of subframes, as shown in FIG. 12B .
  • the radio base station apparatus acquires the CSI of multiple cells from the PUSCHs received on the uplink.
  • the CSI information of multiple cells A, B and C (WB CQIs, WB PMI (W1), WB PMI (W2), SB position information, the average CQI values of M selected subbands, and the optimal PMIs for the average CQI value) is complete.
  • the new PUSCH reporting mode extended mode 2-2, transmission mode 9 using a double codebook
  • the amount of information of CSI feedback information with the conventional PUSCH reporting mode can be reduced.
  • a case will be described here with this embodiment where a user terminal feeds back CSI of each cell adopting CoMP.
  • a case has been described with the above embodiments where a user terminal feeds back each cell's CSI to the radio base station apparatus of a predetermined cell (serving cell) among a plurality of cells adopting CoMP (see FIG. 13A ).
  • a user terminal may feed back each cell's CSI to the radio base station apparatus of the corresponding cell.
  • the user terminal feeds back the CSI of the serving cell to the serving cell and feeds back the CSI of other cells (coordinated cells) to the corresponding coordinated cells (see FIG. 13B ).
  • the user terminal may feed back the cells' CSI all together.
  • the CSI of the cells is fed back to the cell of the better uplink performance between the serving cell and the coordinated cell.
  • FIG. 13C it is also possible to switch the cell to feed back CSI to, on a dynamic basis.
  • the above first embodiment and the second embodiment can be applied as appropriate.
  • FIG. 14 is a diagram to explain a system configuration of a radio communication system according to the present embodiment.
  • the radio communication system shown in FIG. 14 is a system to accommodate, for example, the LTE system or SUPER 3G.
  • carrier aggregation to group a plurality of fundamental frequency blocks into one, where the system band of the LTE system is one unit, is used.
  • this radio communication system may be referred to as “IMT-Advanced” or may be referred to as “4G.”
  • the radio communication system 1 is configured to include radio base station apparatuses 20 A and 20 B to constitute transmission points, and a plurality of first and second user terminals 10 A and 10 B that communicate with these radio base station apparatuses 20 A and 20 B.
  • the radio base station apparatuses 20 A and 20 B are connected with a higher station apparatus 30 , and this higher station apparatus 30 is connected with a core network 40 .
  • the radio base station apparatuses 20 A and 20 B are connected with each other by wire connection or by wireless connection.
  • the first and second user terminals 10 A and 10 B are able to communicate with the radio base station apparatuses 20 A and 20 B in cells C1 and C2.
  • the higher station apparatus 30 may be, for example, an access gateway apparatus, a radio network controller (RNC), a mobility management entity (MME) and so on, but is by no means limited to these. Also, between cells, when necessary, CoMP transmission is controlled by a plurality of base stations.
  • RNC radio network controller
  • MME mobility management entity
  • first and second user terminals 10 A and 10 B may be either LTE terminals or LTE-A terminals, the following description will be given simply with respect to the first and second user terminals, unless specified otherwise. Also, although the first and second user terminals 10 A and 10 B will be described to perform radio communication with the radio base station apparatuses 20 A and 20 B, for ease of explanation, more generally, user equipment (UE) to include both mobile terminal apparatuses and fixed terminal apparatuses may be used as well.
  • UE user equipment
  • OFDMA Orthogonal Frequency Division Multiple Access
  • SC-FDMA Single-Carrier Frequency Division Multiple Access
  • OFDMA is a multi-carrier transmission scheme to perform communication by dividing a frequency band into a plurality of narrow frequency bands (subcarriers) and mapping data to each subcarrier.
  • SC-FDMA is a single carrier transmission scheme to reduce interference between terminals by dividing, per terminal, the system band into bands formed with one or continuous resource blocks, and allowing a plurality of terminals to use mutually different bands.
  • Downlink communication channels include a PDSCH (Physical Downlink Shared Channel), which is used by the first and second user terminals 10 A and 10 B on a shared basis as a downlink data channel, and downlink L1/L2 control channels (PDCCH, PCFICH, PHICH). Transmission data and higher control signals (including PUSCH reporting mode command information) are transmitted by the PDSCH. Scheduling information for the PDSCH and the PUSCH and so on are transmitted by the PDCCH (Physical Downlink Control Channel). The number of OFDM symbols to use for the PDCCH is transmitted by the PCFICH (Physical Control Format Indicator Channel). HARQ ACK and NACK for the PUSCH are transmitted by the PHICH (Physical Hybrid-ARQ Indicator Channel).
  • PDSCH Physical Downlink Shared Channel
  • PCFICH Physical Control Format Indicator Channel
  • HARQ ACK and NACK for the PUSCH are transmitted by the PHICH (Physical Hybrid-ARQ Indicator Channel).
  • Uplink communication channels include a PUSCH (Physical Uplink Shared Channel), which is used by each user terminal on a shared basis as an uplink data channel, and a PUCCH (Physical Uplink Control Channel), which is an uplink control channel. Transmission data, downlink received quality information (CQI), ACK/NACK, and furthermore higher control information are transmitted by means of this PUSCH. Furthermore, the PUCCH transmits downlink received quality information (CQI), ACK/NACK, and so on.
  • PUSCH Physical Uplink Shared Channel
  • PUCCH Physical Uplink Control Channel
  • radio base station apparatus 20 An overall configuration of the radio base station apparatus according to the present embodiment will be described with reference to FIG. 15 .
  • the radio base station apparatuses 20 A and 20 B have the same configuration and therefore hereinafter will be described simply as “radio base station apparatus 20 .”
  • the first and second user terminals 10 A and 10 B which will be described later, also have the same configuration and therefore hereinafter will be described simply as “user terminal 10 .”
  • the radio base station apparatus 20 includes transmitting/receiving antennas 201 , amplifying sections 202 , transmitting/receiving sections (reporting sections) 203 , a baseband signal processing section 204 , a call processing section 205 , and a transmission path interface 206 .
  • Transmission data to be transmitted from the radio base station apparatus 20 to the user terminal on the downlink is input from the higher station apparatus 30 into the baseband signal processing section 204 via the transmission path interface 206 .
  • a signal of a downlink data channel is subjected to a PDCP layer process, division and coupling of transmission data, RLC (Radio Link Control) layer transmission processes such as an RLC retransmission control transmission process, MAC (Medium Access Control) retransmission control, including, for example, an HARQ transmission process, scheduling, transport format selection, channel coding, an inverse fast Fourier transform (IFFT) process, and a precoding process.
  • RLC Radio Link Control
  • MAC Medium Access Control
  • a signal of a physical downlink control channel which is a downlink control channel, is also subjected to transmission processes such as channel coding and an inverse fast Fourier transform.
  • the baseband signal processing section 204 reports control information for allowing each user terminal 10 to perform radio communication with the radio base station apparatus 20 , to the user terminals 10 connected to the same cell, by a broadcast channel.
  • the information for allowing communication in the cell includes, for example, the uplink or downlink system bandwidth, root sequence identification information (root sequence index) for generating random access preamble signals in the PRACH (Physical Random Access Channel), and so on.
  • Baseband signals that are output from the baseband signal processing section 204 are converted into a radio frequency band in the transmitting/receiving sections 203 .
  • the amplifying sections 202 amplify the radio frequency signals having been subjected to frequency conversion, and output the results to the transmitting/receiving antennas 201 .
  • the transmitting/receiving sections 203 constitute a receiving section configured to receive uplink signals including the CQIs and PMIs of multiple cells, and a transmitting section configured to transmit transmission signals by coordinated multiple point transmission.
  • radio frequency signals received in the transmitting/receiving antennas 201 are amplified in the amplifying sections 202 , converted into baseband signals through frequency conversion in the transmitting/receiving sections 203 , and input in the baseband signal processing section 204 .
  • the baseband signal processing section 204 performs an FFT process, an IDFT process, error correction decoding, a MAC retransmission control receiving process, and RLC layer and PDCP layer receiving processes, of the transmission data that is included in the baseband signal received on the uplink.
  • the decoded signals are transferred to the higher station apparatus 30 through the transmission path interface 206 .
  • the call processing section 205 performs call processing such as setting up and releasing communication channels, manages the state of the radio base station apparatus 20 and manages the radio resources.
  • FIG. 16 is a block diagram showing a configuration of a baseband signal processing section in the radio base station apparatus shown in FIG. 15 .
  • the baseband signal processing section 204 is primarily formed with a layer 1 processing section 2041 , a MAC processing section 2042 , an RLC processing section 2043 , a CSI updating section 2044 , a CST acquiring section 2045 , and a reporting mode determining section 2046 .
  • the layer 1 processing section 2041 mainly performs processes related to the physical layer.
  • the layer 1 processing section 2041 performs processes for a signal received on the uplink, including, for example, channel decoding, a discrete Fourier transform (DFT), frequency demapping, an inverse fast Fourier transform (IFFT), data demodulation and so on.
  • the layer 1 processing section 2041 performs processes for a signal to transmit on the downlink, including channel coding, data modulation, frequency mapping, an inverse fast Fourier transform (IFFT) and so on.
  • DFT discrete Fourier transform
  • IFFT inverse fast Fourier transform
  • the MAC processing section 2042 performs processes such as MAC layer retransmission control for a signal that is received on the uplink, scheduling for the uplink/downlink, transport format selection for the PUSCH/PDSCH, resource block selection for the PUSCH/PDSCH and so on.
  • the RLC processing section 2043 performs, for a packet that is received on the uplink/a packet to transmit on the downlink, packet division, packet combining, RLC layer retransmission control and so on.
  • the CSI acquiring section 2045 acquires each cell's CSI (for example, CQI), fed back from the user terminal using the PUSCH.
  • the content of CSI to be fed back from the user terminal varies depending on the PUSCH reporting mode.
  • the content of channel state information of multiple cells WB CQIs, SB CQIs, WB PMIs, SB PMIs, average CQI values, PMIs for average CQI values
  • WB CQIs, SB CQIs, WB PMIs, SB PMIs, average CQI values, PMIs for average CQI values is allotted to PUSCHs in a plurality of subframes. For example, in the case of above FIG.
  • channel state information of three cells A, B and C (WB CQIs and SB CQIs) is allotted to PUSCHs in three subframes and transmitted from the user terminal, so that it is possible to acquire each CoMP cell's channel state information (WB CQIs and SB CQIs) by receiving the three subframe of PUSCHs.
  • the CSI updating section 2044 Based on each cell's CSI acquired in the CSI acquiring section 2045 , the CSI updating section 2044 recalculates and updates CSI (for example, CQI). When one of the first to eighth modes is applied, each cell's WB CQI, SB CQIs and so on are allotted to PUSCHs in a plurality of subframes and fed back, so that the CSI updating section 2044 is able to update CSI based on the latest CSI of each cell from CSI feedback information with reduced overhead.
  • CSI for example, CQI
  • the reporting mode determining section 2046 determines the reporting mode for selecting the channel state information which the user terminal feeds back using the PUSCH.
  • the reporting mode determining section 2046 is able to determine the PUSCH reporting mode based on the channel state information acquired in the CSI acquiring section 2045 or the CSI update value calculated in the CSI updating section 2044 , and so on.
  • the PUSCH reporting mode is determined from extended mode 1-2, extended mode 2-0, extended mode 2-2, extended mode 3-0 and extended mode 3-1. Obviously, the reporting mode is not limited to these.
  • the PUSCH reporting mode determined in the reporting mode determining section 2046 is reported to the user terminal via the transmitting/receiving sections 203 through higher layer signaling and so on.
  • a user terminal 10 has transmitting/receiving antennas 101 , amplifying sections 102 , transmitting/receiving sections (receiving sections) 103 , a baseband signal processing section 104 , and an application section 105 .
  • radio frequency signals that are received in the transmitting/receiving antennas 101 are amplified in the amplifying sections 102 , and subjected to frequency conversion and converted into baseband signals in the transmitting/receiving sections 103 .
  • the baseband signals are subjected to receiving processes such as an FFT process, error correction decoding and retransmission control, in the baseband signal processing section 104 .
  • downlink transmission data is transferred to the application section 105 .
  • the application section 105 performs processes related to higher layers above the physical layer and the MAC layer. Also, in the downlink data, broadcast information is also transferred to the application section 105 .
  • uplink transmission data is input from the application section 105 into the baseband signal processing section 104 .
  • the baseband signal processing section 104 performs a mapping process, a retransmission control (HARQ) transmission process, channel coding, a DFT process, and an IFFT process.
  • Baseband signals that are output from the baseband signal processing section 104 are converted into a radio frequency band in the transmitting/receiving sections 103 .
  • the amplifying sections 102 amplify the radio frequency signals having been subjected to frequency conversion, and transmit the results from the transmitting/receiving antennas 101 .
  • the transmitting/receiving sections 103 constitute a transmitting means to transmit information about phase differences, information about the connecting cells, selected PMIs and so on to the radio base station apparatus eNBs of a plurality of cells, and a receiving means to receive downlink signals.
  • FIG. 18 is a block diagram showing a configuration of a baseband signal processing section in the user terminal shown in FIG. 17 .
  • the baseband signal processing section 104 is primarily formed with a layer 1 processing section 1041 , a MAC processing section 1042 , an RLC processing section 1043 , a feedback information generating section 1044 , and a CSI determining section 1045 .
  • the layer 1 processing section 1041 mainly performs processes related to the physical layer.
  • the layer 1 processing section 1041 performs processes for a signal that is received on the downlink, including, for example, channel decoding, a discrete Fourier transform (DFT), frequency demapping, an inverse fast Fourier transform (IFFT), data demodulation and so on.
  • the layer 1 processing section 1041 performs processes for a signal to transmit on the uplink, including channel coding, data modulation, frequency mapping, an inverse fast Fourier transform (IFFT), and so on.
  • DFT discrete Fourier transform
  • IFFT inverse fast Fourier transform
  • the MAC processing section 1042 performs, for a signal that is received on the downlink, MAC layer retransmission control (HARQ), an analysis of downlink scheduling information (specifying the PDSCH transport format and specifying the PDSCH resource blocks) and so on. Also, the MAC processing section 1042 performs processes for a signal to transmit on the uplink, such as MAC retransmission control, an analysis of uplink scheduling information (specifying the PUSCH transport format and specifying the PUSCH resource blocks) and so on.
  • HARQ MAC layer retransmission control
  • processes for a signal to transmit on the uplink such as MAC retransmission control, an analysis of uplink scheduling information (specifying the PUSCH transport format and specifying the PUSCH resource blocks) and so on.
  • the RLC processing section 1043 performs, for a packet received on the downlink/a packet to transmit on the uplink, packet division, packet combining, RLC layer retransmission control, and so on.
  • the CSI determining section 1045 determines each cell's channel state information (WB CQI, WB PMI, SB CQIs, SB PMIs, WB RI and so on). For example, the CSI determining section 1045 calculates WB CQIs and SB CQIs from the desired signals of the cells, interference signals, interference of cells apart from the CoMP set, thermal noise and so on. Each cell's CSI, determined in the CSI determining section 1045 , is output to the feedback information generating section 1044 .
  • the feedback information generating section 1044 generates feedback information (CSI and so on).
  • the CSI may include each cell's WB CQI, WB PMI, SB CQIs, SB PMIs, WB RI, phase difference information and so on.
  • the feedback information generating section 1044 generates feedback information based on the reporting mode determined in and reported from the reporting mode determining section 2046 of the radio base station apparatus.
  • the feedback information generating section 1044 also generates retransmission control signals (ACK/NACK), which show whether or not the user terminal has received data signal adequately, as feedback information. These signals generated in the feedback information generating section 1044 are fed back to the radio base station apparatus using the PUSCH or the PUCCH.
  • ACK/NACK retransmission control signals
  • the feedback information generating section 1044 generates feedback information such that channel state information of multiple cells is allotted to PUSCHs in multiple subframes and transmitted.
  • the feedback information generating section 1044 generates feedback information such that, in the PUSCH in one subframe, the SB CQIs of multiple cells and the WB CQI of one cell are arranged, the WB CQIs of different cells are arranged between subframes, and the SB CQIs of all cells are allotted within a predetermined number of subframes. In this way, the SB CQIs of all cells (part of the subbands) are allotted to be included in the PUSCH of one subframe, so that an effect of reducing the feedback delay can be achieved.
  • the feedback information generating section 1044 In the case of extended mode 1-2 to report SB PMIs and WB CQIs, the feedback information generating section 1044 generates feedback information such that, in the PUSCH in one subframe, the SB PMIs of multiple cells and the WB CQI of one cell are arranged, the WB CQIs of varying cells are arranged between subframes, and the SB PMIs of all cells are allotted within a predetermined number of subframes. In this way, in the PUSCH to be transmitted in one subframe, all the SB PMIs of the same cell are arranged, so that an effect of reducing the feedback delay can be achieved.
  • the feedback information generating section 1044 generates feedback information such that, in the PUSCH of one subframe, one cell's WB CQI, the SB CQIs of another cell and position information of the SB CQIs of the other cell are arranged, the WB CQIs of different cells are arranged between subframes, and the SB CQIs of other cells and position information of the SB CQIs of other cells are arranged.
  • the feedback information generating section 1044 generates feedback information such that, in the PUSCH of one subframe, one cell's WB CQI, the SB CQIs of that cell, the WB PMI of another cell, the SB PMIs of the other cell, and position information of the SB PMIs of the other cell are arranged, and different WB CQIs, WB PMIs, SB CQIs and SB PMIs are arranged between subframes.
  • each cell's CSI (WB CQI, WB PMI, SB CQIs, SB PMIs, WB RI and so on) is calculated in the CSI determining section 1045 of the user terminal. Then, the determined CSI is output to the feedback information generating section 1044 .
  • the feedback information generating section 1044 generates feedback information such that channel state information of multiple cells is allotted to and transmitted in PUSCHs in a plurality of subframes. At this time, the feedback information generating section 1044 selects the CSI to feed back based on the reporting mode determined in and reported from the reporting mode determining section 2046 of the radio base station apparatus. Then, the feedback information generating section 1044 feeds back each cell's CSI to the radio base station apparatus.
  • the radio base station apparatus updates CSI using the CSI of multiple cells fed back from the user terminal. Also, the reporting mode determining section 2046 of the radio base station apparatus determines the reporting mode based on CSI that is fed back or the updated value of CSI, and reports it to the user terminal.

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JP2012067844A JP5878406B2 (ja) 2012-03-23 2012-03-23 無線通信システム、ユーザ端末、無線基地局装置及び無線通信方法
PCT/JP2013/058087 WO2013141301A1 (ja) 2012-03-23 2013-03-21 無線通信システム、ユーザ端末、無線基地局装置及び無線通信方法

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